Highly Stretchable Polymer Composite with Strain‐Enhanced Electromagnetic Interference Shielding Effectiveness

Yao, Bin; Hong, Wei; Chen, Tianwu; Han, Zhubing; Xu, Xinwei; Hu, Renchao; Hao, Jianyu; Li, Changhao; He, Li; Perini, Steve; Lanagan, Michael T.; Zhang, Sulin; Wang, Qing; Wang, Hong

doi:10.1002/adma.201907499

Cited by 301 publications

(199 citation statements)

References 46 publications

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“…LM has been infused into the pores of existing elastomer foams [17] to create a conductive rather than a dielectric composite. [18] Here, the LM is dispersed in the foam walls and the pores of the foam remain filled with air; we call this porous structure 'liquid metal elastomer foam' (LMEF). The LMEF is extremely soft, has good compressibility, and the ε r changes significantly in response to strain.…”

Section: Introductionmentioning

confidence: 99%

Ultrasoft Liquid Metal Elastomer Foams with Positive and Negative Piezopermittivity for Tactile Sensing

Yang

Tang

et al. 2020

Adv Funct Materials

182

134

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Soft, capacitive tactile (pressure) sensors are important for applications including human–machine interfaces, soft robots, and electronic skins. Such capacitors consist of two electrodes separated by a soft dielectric. Pressing the capacitor brings the electrodes closer together and thereby increases capacitance. Thus, sensitivity to a given force is maximized by using dielectric materials that are soft and have a high dielectric constant, yet such properties are often in conflict with each other. Here, a liquid metal elastomer foam (LMEF) is introduced that is extremely soft (elastic modulus 7.8 kPa), highly compressible (70% strain), and has a high permittivity. Compressing the LMEF displaces the air in the foam structure, increasing the permittivity over a large range (5.6–11.7). This is called “positive piezopermittivity.” Interestingly, it is discovered that the permittivity of such materials decreases (“negative piezopermittivity”) when compressed to large strain due to the geometric deformation of the liquid metal droplets. This mechanism is theoretically confirmed via electromagnetic theory, and finite element simulation. Using these materials, a soft tactile sensor with high sensitivity, high initial capacitance, and large capacitance change is demonstrated. In addition, a tactile sensor powered wirelessly (from 3 m away) with high power conversion efficiency (84%) is demonstrated.

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Section: Introductionmentioning

confidence: 99%

Ultrasoft Liquid Metal Elastomer Foams with Positive and Negative Piezopermittivity for Tactile Sensing

Yang

Tang

et al. 2020

Adv Funct Materials

182

134

View full text Add to dashboard Cite

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“…However, the composites consisting of liquid metal micro/nano particles may demonstrate the stretch-enhanced conductivity [ 54 ]. For example, Wang et al reported that the electrical conductivity of the 3D LM composite increases monotonically with applied tensile strain, from 5.3 × 10 5 S/m under the stretch-free condition to 1.1 × 10 6 S/m at 400% strain ( Figure 3 d) [ 55 ]. Similarly, a liquid metal-filled magnetorheological elastomer shows the minimum conductivity in the relaxed state and increases drastically under any deformation ( Figure 3 e) [ 56 ].…”

Section: Propertiesmentioning

confidence: 99%

“…Copyright (2013) WILEY-VCH. ( d ) Electrical conductivity as a function of the strain of the composites [ 55 ]. Copyright (2020) WILEY-VCH.…”

Section: Figurementioning

confidence: 99%

Liquid Metal Based Flexible and Implantable Biosensors

et al. 2020

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Biosensors are the core elements for obtaining significant physiological information from living organisms. To better sense life information, flexible biosensors and implantable sensors that are highly compatible with organisms are favored by researchers. Moreover, materials for preparing a new generation of flexible sensors have also received attention. Liquid metal is a liquid-state metallic material with a low melting point at or around room temperature. Owing to its high electrical conductivity, low toxicity, and superior fluidity, liquid metal is emerging as a highly desirable candidate in biosensors. This paper is dedicated to reviewing state-of-the-art applications in biosensors that are expounded from seven aspects, including pressure sensor, strain sensor, gas sensor, temperature sensor, electrical sensor, optical sensor, and multifunctional sensor, respectively. The fundamental scientific and technological challenges lying behind these recommendations are outlined. Finally, the perspective of liquid metal-based biosensors is present, which stimulates the upcoming design of biosensors.

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“…Thus, hardware dielectric materials with low- D k and low- D f characteristics are in demand for the 5G combination construction. Another important developing trend for research and development of 5G telecommunication is the combination with advanced display techniques, such as wearable display, health monitoring display, and so on [ 8 ]. Thus, among the new materials developed for 5G applications, advanced fabrics or fibrous membranes with low- D k and low- D f features have occupied important positions [ 9 ].…”

Section: Introductionmentioning

confidence: 99%

Preparation and Characterization of Electrospun Fluoro-Containing Poly(imide-benzoxazole) Nano-Fibrous Membranes with Low Dielectric Constants and High Thermal Stability

et al. 2021

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The rapid development of advanced high-frequency mobile communication techniques has advanced urgent requirements for polymer materials with high-temperature resistance and good dielectric properties, including low dielectric constants (low-Dk) and low dielectric dissipation factors (low-Df). The relatively poor dielectric properties of common polymer candidates, such as standard polyimides (PIs) greatly limited their application in high-frequency areas. In the current work, benzoxazole units were successfully incorporated into the molecular structures of the fluoro-containing PIs to afford the poly(imide-benzoxazole) (PIBO) nano-fibrous membranes (NFMs) via electrospinning fabrication. First, the PI NFMs were prepared by the electrospinning procedure from organo-soluble PI resins derived from 2,2’-bis(3,4-dicarboxy-phenyl)hexafluoropropane dianhydride (6FDA) and aromatic diamines containing ortho-hydroxy-substituted benzamide units, including 2,2-bis[3-(4-aminobenzamide)-4-hydroxylphenyl]hexafluoropropane (p6FAHP) and 2,2-bis[3-(3-aminobenzamide)-4-hydroxyphenyl]hexafluoropropane (m6FAHP). Then, the PI NFMs were thermally dehydrated at 350 °C in nitrogen to afford the PIBO NFMs. The average fiber diameters (dav) for the PIBO NFMs were 1225 nm for PIBO-1 derived from PI-1 (6FDA-p6FAHP) precursor and 816 nm for PIBO-2 derived from PI-2 (6FDA-m6FAHP). The derived PIBO NFMs showed good thermal stability with the glass transition temperatures (Tgs) over 310 °C and the 5% weight loss temperatures (T5%) higher than 500 °C in nitrogen. The PIBO NFMs showed low dielectric features with the Dk value of 1.64 for PIBO-1 and 1.82 for PIBO-2 at the frequency of 1 MHz, respectively. The Df values were in the range of 0.010~0.018 for the PIBO NFMs.

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Highly Stretchable Polymer Composite with Strain‐Enhanced Electromagnetic Interference Shielding Effectiveness

Cited by 301 publications

References 46 publications

Ultrasoft Liquid Metal Elastomer Foams with Positive and Negative Piezopermittivity for Tactile Sensing

Ultrasoft Liquid Metal Elastomer Foams with Positive and Negative Piezopermittivity for Tactile Sensing

Liquid Metal Based Flexible and Implantable Biosensors

Preparation and Characterization of Electrospun Fluoro-Containing Poly(imide-benzoxazole) Nano-Fibrous Membranes with Low Dielectric Constants and High Thermal Stability

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